The metal casting process is extensively used in manufacturing because of its manyadvantages.1. Molten material can flow into very small sections so that intricate shapes can bemade by this process. As a result, many other operations, such as machining,forging, and welding, can be minimized or eliminated.2. It is possible to cast practically any material that is fer rous or non-ferrous.3. As the metal can be placed exactly where it is required, large saving in weight canbe achieved.4. The necessary tools required for casting molds are very simple and inexpensive. Asa result, for production of a small lot, it is the ideal process.5. There are certain parts made from metals and alloys that can only be processed thisway.6. Size and weight of the product is not a limitation for the casting process.

Limitations

1. Dimensional accuracy and surface finish of the castings made by sand castingprocesses are a limitation to this technique. Many new casting processes have beendeveloped which can take into consideration the aspects of dimensional accuracy andsurface finish. Some of these processes are die casting process, investment castingprocess, vacuum-sealed molding process, and shell molding process.2. The metal casting process is a labor intensive process

History

Casting technology, according to biblical records, reaches back almost 5,000 years BC.Gold, pure in nature, most likely caught Prehistoric man's fancy. as he probablyhammered gold ornaments out of the gold nuggets he found. Silver would have beentreated similarly. Mankind next found copper, because it appeared in the ash of his campfires from copper-bearing ore that he lined his fire pits with. Man soon found that copperwas harder than gold or silver. Copper did not bend up when used. So copper, found a

'nitch' in man's early tools, and then marched it's way into Weaponry. But, long before allthis.man found clay. So he made pottery - something to eat from. Then he thought,"now.what else can I do with this mud." . Early man thought about it, "they used thispottery stuff, ( the first patterns ), to shape metal into bowls ".

3200 B.C.

A copper frog, the oldest known casting in existence, is cast in Mesopotamia.

233 B.C.

Cast iron plowshares are poured in China.

500 A.D.

Cast crucible steel is first produced in India, but the process is lost u ntil 1750,when Benjamin Huntsman reinvents it in England.

1455

Dillenburg Castle in Germany is the first to use cast iron pipe to transport water.

1480

Birth of Vannoccio Biringuccio (1480-1539), the "father of the foundry industry,"in Italy. He is the first man to document the foundry process in writing.

1709

Englishman Abraham Darby creates the first true foundry flask for sand and loammolding.

1750

Benjamin Huntsman reinvents the process of cast crucible steel in England. Thisprocess is the first in which the steel is completely melted, producing a uniformcomposition within the melt. Since the metal is completely molten, it also allows for alloysteel production, as the additional elements in the alloy can be added to the crucibleduring melting. Prior steel production was accomplished by a combination of forging and tempering, and the metal never reached a molten state.

1809

Centrifugal casting is developed by A. G. Eckhardt of Soho, England.

1896

American Foundrymen's Association (renamed American Foundrymen's Society in1948 and now called the American Foundry Society) is formed.

1897

Investment casting is rediscovered by B.F. Philbrook of Iowa. He uses it to castdental inlays.

1947

The Shell process, invented by J. Croning of Germany during WWII, is discoveredby U.S. officials and made public.

1953

The Hotbox system of making and curing cores in one operation is developed,eliminating the need for dielectric drying ovens.

1958

H.F. Shroyer is granted a patent for the full mold process, the forerunner of theexpendable pattern (lost foam) casting process.

1968

The Coldbox process is introduced by L. Toriello and J. Robins for high productioncore making.

1971

The Japanese develop V-Process molding. This method uses unbonded sand and avacuum.

1971

Rheocasting is developed at Massachusetts Institute of Technology.

1996

Cast metal matrix composites are first used in a production model automobile in thebrake rotors for the Lotus Elise.

Metal Casting History (India)3000 BC

Earliest castings include the 11 cm high bronze dancing girl found at Mohen -jo-daro.

2000 BC

Iron pillars, arrows, hooks, nails, bowls and daggers or earlier have been foundin Delhi, Roopar, Nashik and other places.

500 BC

Large scale state-owned mints and jewelry units, and processes of metalextraction and alloying have been mentioned in Kautilya's

Arthashastra

500 A.D.

Cast crucible steel is first produced in India, but the process is lost until 1750,when Benjamin Huntsman reinvents it in England.

LECTURE: 1Casting Terms (Click on the

figure 1

to view)

1. Flask: A metal or wood frame, without fixed top or bottom, in which the mold isformed. Depending upon the position of the flask in the molding structure, it isreferred to by various names such as drag - lower molding flask, cope - upper moldingflask, cheek - intermediate molding flask used in three piece molding.2. Pattern: It is the replica of the final object to be made. The mold cavi ty is made withthe help of pattern.3. Parting line: This is the dividing line between the two molding flasks that makes upthe mold.4. Molding sand: Sand, which binds strongly without losing its permeability to air orgases. It is a mixture of silica sand, clay, and moisture in appropriate proportions.5. Facing sand: The small amount of carbonaceous material sprinkled on the innersurface of the mold cavity to give a better surface finish to the castings.